The singlet-triplet energy gap in organic and Pt-containing phenylene ethynylene polymers and monomers

The singlet S₁-triplet T₁ energy gap in organic and Pt-containing phenylene ethynylene polymers and monomers was analyzed. Direct measurements of fluorescence and phosphorescence were used to determine the S₁ and T₁ energies in a series of conjugated polymers. The spin orbit coupling increased with the inclusion of platinum, so T₁ state emission was easier to detect. For the platinum containing polymer series and for the all-organic polymers, results showed the T₁ state to be at a constant separation of 0.7±0.1 eV below the singlet S₁ state.